Internal combustion engines



Aug. 26, 1969 J, A. POPE ETAL INTERNAL COMBUSTION mamas Filed March 29, 1967 5 Sheets-Sheet 2- QQN 8m svw 3% r f q 3mm? 0 & V

INVENTORS Joseph ,4 Papa John 55. Al 1.5g

Aug. 26, 1969 J. A. POPE ETA!- 3,463,

I INTERNAL COMBUSTION ENGINES Filed March 29, 1967 I 3 Sheets-Sheet 5 INVENTORS dqseph APQP: John Elia p453 United States Patent US. Cl. 123--196 Claims ABSTRACT OF THE DISCLOSURE In large opposed piston ignition engines it may be necessary to circulate the oil when the engine is not running. The engine is provided with a lubricant extractor to remove oil from the inverted pistons of the engine, when the engine is not running, in order to prevent the overflow of the oil from the piston skirt.

This invention relates to internal combustion engines and is particularly, though not exclusively, applicable to large compression ignition engines of the order of 2000 B.H.P. and over, of the so-called opposed piston type, the cylinders of which are usually upright.

In such large engines which are usually multi-cylinder it is sometimes necessary to circulate the lubricating oil round the engine for a period of time before starting up and/or after shut down while the engine is stationary. Such circulation after shut down is to prevent for one thing the oil in any pistons from forming carbon on the inside surfaces of the piston thereby reducing the thermal conductivity from the piston to the oil. This circulation is usually achieved by having independent electrically driven oil pumps. On opposed piston engines of the kind referred to, a few further problems occur when thus circulating the oil after shutdown. The oil will enter the inverted upper piston via the big-end bearings and the connecting rods. One of such inverted pistons of any such multicylinder engine may be close to the inner dead centre position and it would be possible for the piston and the liner above it, to become filled with oil, thereby creating a pressure head of oil. This could lead to leakage past the piston rings, and filling of the combustion chamber, which could result in hydraulic locking of inwardly moving opposed pistons, or dangerous combustion conditions. A further problem could result from such leakage of oil entering the exhaust ports so causing fouling due to the formation of carbon deposits, and loss of engine performance.

The object of the present invention is to solve at least one of these problems, or at least to modify the same.

According to the present invention an internal combustion engine having means for circulating lubricating fluid While the engine is stationary and having at least one inverted piston, is characterised by lubricant extractor means, operable while the engine is stationary, arranged to extract lubricant from each such inverted piston at least to a level to prevent overflow from the piston skirt.

The internal combustion engine aforesaid may be further characterised in that the lubricant extracting means includes a station ary dip tube.

In the accompanying drawings:

FIG. 1 is a diagram illustrating a conventional arrangement for a pair of pistons of an opposed piston engine;

FIG. 2 is a diagram showing the upper inverted piston of FIG. 1 modified in accordance with one example of the invention;

FIG. 3 shows diagrammatically an ejector applied to the arrangement of FIG. 2;

FIG. 4 is a general arrangement diagram of a lubricat- 3,463,135 Patented Aug. 26, 1969 ing system for an internal combustion engine having four inverted pistons;

FIGS. 5 and 6 show diagrammatically two positions of a timing valve for use in the arrangement of FIG. 4;

FIG. 7 shows diagrammatically an alternative system to that shown in FIGS. 5 and 6.

The diagram of FIG. 1 shows one upper and one opposed lower piston 10a and 10b and their connecting rods 13a and 13b respectively of an opposed piston engine the pistons being located in a common cylinder 11 with ports 12a, 12b.

FIG. 2 shows the upper piston 10a of FIG. 1 to an enlarged scale with a dip pipe 14 the lower end of which is at all times below the top of the piston skirt which is made longer than the stroke of the piston and which skirt for obvious reasons is imperforate, the piston being shown at its inner dead centre position.

FIG. 3 shows an ejector 15, the suction pipe 16 of Which is connected to the dip pie 14 for the piston 10a shown in its outermost position in full lines, its lowermost position being shown in dotted outline. For marine use the relative overlap of the dip pipe and the top of the piston skirt when in the dotted position must be such as to allow for roll and pitch of the vessel so that spill-over is prevented.

FIG. 4 is one example of a general arrangement for the lubricating system of a multicylinder opposed piston internal combustion engine and shows lubrication pumps 17a, 17b for the upper and lower crankshafts of which only the upper crankshaft 18 is shown. These pumps are connected to electric motors 19a, 19b. Coupled to the upper crankshaft 18 is a control pump 20 the output side of which is connected by a pipe 20a to a bobbin valve 21, bias loaded against pressure from the control pump by a return spring 22. From the bobbin valve 21 are pipes 21a, 21b and 21c leading to the lower and upper orankshafts and to ejectors 23 respectively for the four inverted pistons 24a, 24b, 24c and 24d of the engine. The reservoirs for the pumps are shown in conventional manner. In a modification, instead of providing the return spring 22 the bobbin valve can be constructed and arranged for gravity bias loading.

FIGS. 5 and 6 show diagrammatically the valve 21 of FIG. 4 respectively in the running position (FIG. 5) with the bias spring 22 compressed by pressure from the pump 20; and in the stopped position (FIG. 6) Where the spring 22 has moved the bobbin 25 to its alternative position. The bobbin has four lands 25a, 25b, 25c and 25d. The pipe connections of the valve are given the same reference characteristics as in FIG. 4. A regulated discharge 2% is provided opposite the pipe connection 20a to control the speed of movement of the bobbin 25.

FIG. 7 shows diagrammatically a simplified system similar to FIG. 4 but omitting the pump 20 and the bobbin valve 21. The electrically driven pump 17b supplying both the pipes 21a and 21b while the pump 17a supplies only the pipe 21c leading to the ejectors 23. A time switch 26 is provided for the motor 19a.

In operation, considering FIGS. 1 to 6, while the engine is running the pumps 17a, 17band 20 are operating and the bobbin 25 (FIG. 5) is under pressure from the pump 20 via the pipe 20a, forcing it to the left against the return spring 22. The lands 25c and 25d isolate the ejector 23 from the pumps 17a and 20* while pumps 17a and 17b supply lubrication respectively to the lubrication pipes 21b and 21a of the upper and lower crankshafts for normal lubrication of the engine, which nowadays includes a coolant circuit to the piston crowns via passages in the connecting rods.

When the engine stops, the pump 20 no longer provides the pressure to hold the valve bobbin 25 against the return spring 22, whereupon the bobbin moves to the righthand position (FIG. 6). The electrically driven pumps 17a and 17b are maintained running preferably under control of a time delay switch (not shown) starting on collapse of pressure from the pump 20 and with manual reset so that these pumps 17a, 1711 can also be started and run before starting the engine. The pump 1711 alone now supplies both the lubrication pipes 21a and 21b while the pump 17b now supplies all the ejectors 23. Since the dip tubes 14 are at all times below the upper ends of the piston skirts, any oil collecting in the pistons after the engine stops is kept below such level and cannot spill over the top edge of the skirt to seep down past the piston rings of the inverted pistons into the combustion space between the opposed pistons, while the pump 17a can continue to provide a cooling circulation of the lubricating oil to the underside of the piston crown, as is known to be required for well known reasons.

In the modified arrangement of FIG. 7 the pump 17a is not operative until the time delay switch 26 is released by the shut down of the engine, after which both pumps continue to run for a predetermined time to the same effect as explained for the arrangement of FIGS. 4 and 6.

The invention is obviously not limited to the details above given by way of example. For instance, an electrically driven suction pump could be used in place of the ejector and other modifications could be made without departing from the scope of the invention as herein foreshadowed.

While described above as applied to an engine normally installed with its cylinder or cylinders vertical, it is also applicable to V type or other engines having the cylinders normally inclined, the extractor means, or piston skirt being accordingly modified as to its construction and disposition so that spillover from the piston skirt of an inverted piston is prevented.

We claim:

1. An internal combustion engine having means for 4 circulating lubricating fluid while the engine is stationary and having at least one inverted piston, characterised by lubricant extractor means, operable While the engine is stationary, arranged to extract lubricant from each such inverted piston at least to a level to prevent overflow from the piston skirt.

2. An internal combustion engine according to claim 1 further characterised in that the lubricant extracting means includes a stationary dip tube.

3. An internal combustion engine according to claim 1 or 2 further characterised in that the extractor means comprises an ejector system actuated by the said lubricant circulating system.

4. An internal combustion engine according to claim 1 or 2 and further characterised by valve control means responsive to the pressure of a control engine-driven pump and arranged to start and stop supplementary lubricant circulating means with the stopping and running of the engine respectively.

5. An internal combustion engine according to claim 4 further characterised in that the supplementary lubricant circulating means is arranged to provide lubricant to the engine crankshaft bearings as well as to ejectors for the extraction of any surplus lubricant from each inverted piston.

6. An internal combustion engine according to claim 4 and further characterised in that the valve control means comprises a bobbin valve normally biased against the pressure of the engine-driven control pump.

References Cited UNITED STATES PATENTS 1,836,637 12/1931 Woolson. 1,892,089 12/1932 Waseige.

HOUSTON S. BELL, 1a., Primary Examiner 

